Syria's state news agency SANA says opposition gunmen have opened fire on aid vehicles in the besieged rebel-held town of Madaya, near the capital Damascus, but no casualties were reported.

A SARQ official said on Wednesday that the convoy, which included vehicles from the International Committee of the Red Cross and the Syrian Arab Red Crescent, was evacuating sick people from Madaya when it came under fire by unknown gunmen.

The official, who spoke on condition of anonymity in line with regulations, said the operation had been completed and people successfully evacuated.

Madaya, which has been besieged by government and allied militiamen for months, gained international attention after harrowing pictures emerged showing emaciated children and starving residents.

SANA said the shooting occurred late Tuesday night delaying operations for several hours.